JDBC之preparedStatement

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直接贴代码案例，理论知识可以从隔壁看看。

prestmtest.java

package PREPAREDSTAMENT;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import org.junit.Test;public class prestmtest {          String url="jdbc:mysql://localhost:3306/data";          String user="root";          String password="123456";          @Test          /*           * 增加          */          public  void testInsert(){            Connection conn=null;            PreparedStatement pstmt=null;            //获取链接对象           try {            Class.forName("com.mysql.jdbc.Driver");             conn=DriverManager.getConnection(url, user, password);                //准备预编译sql语句             String sql="insert into xxb values(?,?,?)";             //执行sql             pstmt=conn.prepareStatement(sql);             //设置参数            pstmt.setInt(1, 4);             pstmt.setString(2, "杨六");             pstmt.setString(3, "女");             int count=pstmt.executeUpdate();             System.out.print("影响了"+count+"行");        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();            throw new RuntimeException(e);        } //throw new RuntimeException(e);           finally{             if(pstmt!=null)                try {                    pstmt.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }             if(conn!=null)                try {                    conn.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }           }          }          /*           * 删除          */    public  void testDelete(){        Connection conn=null;        PreparedStatement pstmt=null;        //获取链接对象     try {        Class.forName("com.mysql.jdbc.Driver");         conn=DriverManager.getConnection(url, user, password);            //准备预编译sql语句         String sql="delete from xxb where sid=?";         //执行sql         pstmt=conn.prepareStatement(sql);         //设置参数         pstmt.setInt(1, 4);         int count=pstmt.executeUpdate();         System.out.print("影响了"+count+"行");    } catch (Exception e) {        // TODO Auto-generated catch block        e.printStackTrace();        throw new RuntimeException(e);    } //throw new RuntimeException(e);     finally{         if(pstmt!=null)            try {                pstmt.close();            } catch (SQLException e) {                // TODO Auto-generated catch block                e.printStackTrace();                throw new RuntimeException(e);            }         if(conn!=null)            try {                conn.close();            } catch (SQLException e) {                // TODO Auto-generated catch block                e.printStackTrace();                throw new RuntimeException(e);            }     }          }          /*           * 修改          */          public  void testUpdate(){            Connection conn=null;            PreparedStatement pstmt=null;            //获取链接对象           try {            Class.forName("com.mysql.jdbc.Driver");             conn=DriverManager.getConnection(url, user, password);                //准备预编译sql语句             String sql="update xxb set sname=? where sid=?";             //执行sql             pstmt=conn.prepareStatement(sql);             //设置参数             pstmt.setString(1, "张三");             pstmt.setInt(2, 1);             int count=pstmt.executeUpdate();             System.out.print("影响了"+count+"行");        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();            throw new RuntimeException(e);        } //throw new RuntimeException(e);           finally{             if(pstmt!=null)                try {                    pstmt.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }             if(conn!=null)                try {                    conn.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }           }                }            /*           * 查询         */          public  void testQuery(){            Connection conn=null;            PreparedStatement pstmt=null;            //获取链接对象           try {            Class.forName("com.mysql.jdbc.Driver");             conn=DriverManager.getConnection(url, user, password);                //准备预编译sql语句             String sql="select *from xxb";             //执行sql             pstmt=conn.prepareStatement(sql);             //遍历             ResultSet rs=pstmt.executeQuery();             while(rs.next()){                 int id=rs.getInt("sid");                 String name=rs.getString("sname");                 String gender=rs.getString("sgender");                 System.out.println(id+" "+name+" "+gender);             }        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();            throw new RuntimeException(e);        } //throw new RuntimeException(e);           finally{             if(pstmt!=null)                try {                    pstmt.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }             if(conn!=null)                try {                    conn.close();                } catch (SQLException e) {                    // TODO Auto-generated catch block                    e.printStackTrace();                    throw new RuntimeException(e);                }           }                }     }

数据库文件

SET FOREIGN_KEY_CHECKS=0;-- ------------------------------  Table structure for `xxb`-- ----------------------------DROP TABLE IF EXISTS `xxb`;CREATE TABLE `xxb` (  `sid` int(11) default NULL,  `sname` varchar(20) default NULL,  `sgender` varchar(20) default NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8;-- ------------------------------  Records -- ----------------------------INSERT INTO `xxb` VALUES ('1','zhangsan','man'), ('2','lisi','woman'), ('3','wangwu','man');

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